The present invention pertains to a furnace used for the pyrolysis of an analytical sample for subsequent analysis.
In the analysis of many organic materials which include halogens, conventional analytical furnaces which employ mullite, alumina or quartz pyrolysis tubes, react with the gaseous products of pyrolysis to provide interfering byproducts with the analysis of certain chemical elements such as oxygen. Thus for example, when fluorinated sample is pyrolized, it produces HF in gaseous form. This reacts with the mullite, alumina or quartz to provide water (H.sub.2 O). When oxygen is the element being detected, the additional oxygen provided by the interfering water byproduct, leads to an erroneous analytical result. The same effect takes place with other halogens but to a lesser extent since they are not as active as fluorine.
There exists a variety of pyrolysis systems utilizing coaxially spaced multiple tubes. Pending U.S. patent application, Ser. No. 480,777 filed on Feb. 16, 1990, entitled COMBUSTION SYSTEM, now U.S. Pat. No. 5,064,617 issued Nov. 12, 1991, assignee, discloses one such system which is oriented in a horizontal direction and which uses mullite as the inner combustion tube material. Such systems, although working well for most samples, suffer the difficulty mentioned above namely the reaction of fluorinated or other halogen containing samples with the pyrolysis tube itself to provide interfering byproducts of pyrolysis which result in inaccurate analytical results.